New York, Aug. 31 (Agencies): While other big-names wobbled at the US Open on Saturday, defending champion Venus Williams stayed solid as a rock, rumbling into the fourth round with a powerful 41-minutes demolition.

The American, seeded second this year behind younger sister Serena, thrashed German Martina Mueller 6-1, 6-2 to stay on track for a third successive Open crown.

While Serena won the French Open in June and deposed Venus at Wimbledon a month later, at least in New York, Venus still rules. The American has now lost just six games in three matches at Flushing Meadows and is looking in sparkling form. She meets either Chanda Rubin or Lisa Raymond next.

Far less convincing on a blustery day six were Monica Seles and Kim Clijsters.

Sixth seed Seles was in the wars again as she fought off a spirited challenge by South Korea’s Cho Yoon-Jeong to reach the fourth round 6-1, 5-7, 6-3. “She was playing really well and I lost my concentration and then the second set,” Seles, champion here in 1991 and 1992, said.

Seventh seed Clijsters recovered from a nightmare start to oust dynamic Russian Vera Zvonareva 1-6, 7-5, 6-4. The Belgian, girlfriend of men’s champion and top seed Lleyton Hewitt, was flattened in the opening set by some impressive power hitting and canny court-craft from the Russian.

But she gradually wrestled control from the 17-year-old to book a clash against either 10th seed Amelie Mauresmo or Switzerland’s Patty Schnyder.

In the men’s draw, 22nd seed Marcelo Rios of Chile retired in his third-round match with right knee tendinitis, giving 14th seed Jiri Novak of the Czech Republic an easy passage into round four. Rios lost the first two sets 6-3, 6-3 before calling it a day.

Serena’s bid to add the US Open to her Wimbledon and French Open crowns picked up speed on Friday night, the world No. 1 moving into the fourth round at Flushing Meadow with a 6-1, 6-1 demolition of Nathalie Dechy.

Wearing a more traditional pink top and black shorts in place of the eye-popping skin-tight, black lycra outfit that drew stares in her opening two matches, Serena needed only 49 minutes to dispose of 26th-seeded Dechy. Serena sported a pink top, slit so her belly button jewellery could be seen, plus matching pink headband, wristbands and shoes with a black dress.

“I’m just getting better,” the American beamed. “ ‘Pretty in Pink’... I love pink, it’s my new favourite colour.

The winner of a record 13 Grand Slam titles never gave Pless a look-in on the Arthur Ashe Stadium Court, serving with great precision and keeping his opponent on the back foot at all times. Sampras will next face Britain’s Greg Rusedski, a runner-up here in 1997, after the Briton pulled out all the stops to beat in-form Thai Paradorn Srichaphan 3-6, 7-6 (7-2), 7-6 (7-5), 6-7 (3-7), 6-4.

Top seed last year but unseeded this time round, Kuerten is the only player since the US Open turned professional in 1968 to have suffered such a steep fall from grace at the tournament in just 12 months.

It has been injuries and hip surgery, however, which have torpedoed his ranking and the former world No.1 one put them all behind him to blow the 2000 champion off court.

“This is the happiest day for me this year on a tennis court,” said Kuerten, who had not beaten a top-10 player all year. I feel like I have nothing to lose now. To tell you the truth I don’t see anything that can put me under pressure. I am just enjoying myself.